1. Field of the Invention
This invention relates to microwave switches and, in particular, relates to a microwave switch having a magnetically retained actuator plate.
2. Description of Related Art
Microwave switches are known for switching microwave signals. One type of microwave switch is the microwave T-switch, which is used to switch connections between four microwave signals received at four ports of the T-switch. In particular, the T-switch is used to allow each port to be connected to each of the three remaining ports, and has three different positions with two pairs of ports being connected in each position.
Referring to FIGS. 1A-1C, a schematic representation of the connection assembly of a typical T-switch 10 is illustrated. The T-switch 10 comprises a plurality of contacts 12-1, 12-2, 12-3 and 12-4 which are each connected to a respective one of four ports. The T-switch also comprises six reeds 14a-14c and 16a-16c. The reeds 14a-14c and 16a-16c are each generally formed of a flat, elongated member formed of, for example, gold-plated beryllium copper. At any given time, one of the outer reeds 14a-14c will be actuated and one of the inner reeds 16a-16c will be actuated, with the remaining reeds not being actuated.
In combination, therefore, the reeds 14a-14c and 16b-16c cooperate to give the T-switch 10 three unique positions, shown respectively in FIGS. 1A-1C. Thus, in a first position of the T-switch 10, shown in FIG. 1A, the reed 14a connects the contact 12-1 to the contact 12-2, and the reed 16a connects the contact 12-3 to the contact 12-4. (The reeds that are actuated and that establish connections between the contacts 12-1, 12-2, 12-3 and 12-4 are shown in solid black lines, and the reeds that are not actuated and that do not establish connections are shown in dashed lines.) In FIG. 1B, the reed 14b connects the contact 12-2 to the contact 12-4, whereas the reed 16b connects the contact 12-1 to the contact 12-3. Finally, in FIG. 1C, the reed 14c connects the contact 12-1 to the contact 12-4, whereas the reed 16c connects the contact 12-2 to the contact 12-3.
In order to allow the position of T-switches to be controlled automatically, T-switches are ordinarily provided with a drive assembly that is used to select between the various T-switch positions. Additionally, in order to allow the position of the switch to be determined electronically, T-switches are sometimes also provided with indicator assemblies which each typically comprise a switch that turns on when the T-switch is in a respective one of the three positions.
Microwave switches are widely used in space applications in which size and weight considerations are of premium importance. It is therefore desirable to provide a microwave switch with drive and indicator assemblies that are as small and as lightweight as possible, so that the overall size and weight of the microwave switch may be reduced.